Low profile antennae such as inverted-L or F antennas are well known in the art. An example of an inverted-F antenna is shown in FIG. 1 of the accompanying drawings. The antenna 100 comprises a feed section 102 coupled to a short circuited inductive stub 104 and a capacitative line 106. The inductive stub 104 is short circuited to a ground plane 108, above which the feed section 102 protrudes by a distance D. The ground plane 108 is open to allow access for the feed section 102 which is electrically insulated 110 from the ground plane 108. The respective lengths L.sub.1, L.sub.2, of the inductive stub 104 and the capacitative line 106 are determined to give a desired resonance frequency and input impedance Z.sub.in to the antenna seen from the antenna feed point 112. The input impedance is dependent upon the position of the feed section 102 and hence lengths L.sub.1 and L.sub.2, and can be made wholly resistive. Typically, this is a 50 OHM impedance in order to match the output or input impedances respectively of commercially available power amplifiers and low noise amplifiers. Further details regarding inverted-L or F antennas may be found in "Small Antennas" ISBN 0 86380 048 3 pages 116-151.
Inverted-F antennas have found particular applications in the radio telephone art where their high gain and omni-directional radiation patterns are particularly suitable. They are also suitable for applications where good frequency selectivity is required. Additionally, since the antennae are relatively small at typical radio telephone frequencies they can be incorporated within the housing of a radio telephone thereby not interfering with the overall aesthetic appeal of the radio telephone and giving it a more attractive appearance than radio telephones having external antennas. By placing the antenna inside the housing of a radio telephone, the antenna is also less likely to be damaged and therefore have a longer useful life. The inverted-F antenna lends itself to planar fabrication, and may suitably be fabricated on the printed circuit board typically used in a radio telephone to support the electronic circuitry, which lends itself to cheap manufacture.
However, despite their relatively small size the fact that radio telephones are becoming smaller and smaller, and more and more complex necessitating a greater amount of electronics within the housing, the space available for the inverted-F antenna is getting smaller and it is becoming more difficult to conveniently fit such antennae inside the housing. Placing such an antenna external to the housing is inconvenient since it must be conductively coupled through the housing to the components on the printed circuit board, and it removes the benefits normally associated with an internal antenna.